This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Bronchopulmonary Dysplasia (BPD) affects approximately one-fourth of very low birth weight infants (VLBW) and results in chronic pulmonary sequelae and the potential for impaired growth and development. Although somatic growth is associated with improved lung function, management of this disorder frequently includes fluid restriction to minimize pulmonary edema. The optimal way to maximize nutritional intake when fluid is restricted and the effects of the common practice of increasing caloric density (above 24 kcal/oz) on growth, calcium metabolism and bone mineral status are unknown. Despite restricted volume intake, providing either preterm formula or human milk fortified to 27 kcal/oz (0.9 kcal/mL) for 6 weeks to VLBW infants with evolving BPD will lead to calcium absorption, bone and somatic growth in infants comparable to infants who do not have BPD and are fed higher volumes of fortified human milk or formula at 24 kcal/oz (0.8 kcal/mL). These results will support the use of high caloric density feedings in infants with BPD to achieve both bone and overall growth outcomes close to those achievable in utero. Weight gain in each group will average 15-20 g/kg/d, consistent with expectations and mean length (1.0 cm/wk) and head circumference (0.8 cm/wk) will similarly increase at in utero levels. Primary Aim: To compare the effects of different feeding strategies on calcium absorption in Very Low Birth Weight (VLBW) infants with and without evolving bronchopulmonary dysplasia (BPD). Secondary Aim: To evaluate growth and body composition in VLBW infants provided 120 kcal/kg/d feeding during hospitalization.